1. Field of the Invention
The invention relates to addition-crosslinking silicone compositions which can provide protective encapsulation of electrical and electronic components exposed to a highly corrosive environment.
2. Description of the Related Art
Large quantities of silicone encapsulation compositions are used to protect electronic circuits from corrosion. Another situation that has become increasingly prevalent is exposure of electronic components to particularly aggressive, sulfur-containing pollutant gases. The silicone encapsulation compositions available hitherto have high permeability to sulfur, hydrogen sulfide, sulfur dioxide, carbon disulfide, and other organylsulfur compounds, and corrosion of the metallic conductors therefore causes failure and shortened lifetimes of these components.
EP1295905A1 describes silicone encapsulation compositions which comprise pulverulent metallic fillers, Cu powder being described here as particularly preferred. However, the solution proposed here using purely metallic surfaces is still insufficiently effective, because only a relatively small effective surface area of the metal is available for the sulfur-gas-scavenging reaction. This solution is moreover associated with numerous further disadvantages such as high price, high density, and adverse attenuation characteristics.